Metasurfaces have pioneered a new avenue for advanced wave-front engineering.Among the various types of metasurfaces,Huygens'metasurfaces are thought to be a novel paradigm for flat optical devices.Enabled by spec...Metasurfaces have pioneered a new avenue for advanced wave-front engineering.Among the various types of metasurfaces,Huygens'metasurfaces are thought to be a novel paradigm for flat optical devices.Enabled by spectrally overlapped electric resonance and magnetic resonance,Huygens'metasurfaces are imparted with high transmission and full phase coverage of 2π,which makes them capable of realizing high-efficiency wave-front control.However,a defect of Huygens'metasurfaces is that their phase profiles and transmissive responses are often sensitive to the interaction of neighboring Huygens'elements.Consequently,the original assigned phase distribution can be distorted.In this work,we present our design strategy of transmissive Huygens'metasurfaces performing anomalous refraction.We illustrate the investigation of Huygens'elements,realizing the overlapping between an electric dipole and magnetic dipole resonance based on cross-shaped structures.We find that the traditional discrete equidistant-phase design method is not enough to realize a transmissive Huygens'surface due to the interaction between neighboring Huygens'elements.Therefore,we introduce an extra optimization process on the element spacing to palliate the phase distortion resulting from the element interaction.Based on this method,we successfully design unequally spaced three-element transmissive metasurfaces exhibiting anomalous refraction effect.The anomalous refractive angle of the designed Huygens'metasurface is 30°,which exceeds the angles of most present transmissive Huygens'metasurfaces.A transmissive efficiency of 83.5%is numerically derived at the operating wavelength.The far-field electric distribution shows that about 93%of transmissive light is directed along the 30°refractive direction.The deflection angle can be tuned by adjusting the number of Huygens'elements in one metasurface unit cell.The design strategies used in this paper can be inspiring for other functional Huygens'metasurface schemes.展开更多
基金National Key RD Program of China(2016YFA0301300)National Natural Science Foundation of China(61671090,61875021)+3 种基金Guangxi Key Laboratory of Wireless Wideband Communication and Signal ProcessingNatural Science Foundation of Beijing Municipality(2192036)Fundamental Research Funds for the Central UniversitiesFund of State Key Laboratory of IPOC(BUPT)(IPOC2019ZZ03)
文摘Metasurfaces have pioneered a new avenue for advanced wave-front engineering.Among the various types of metasurfaces,Huygens'metasurfaces are thought to be a novel paradigm for flat optical devices.Enabled by spectrally overlapped electric resonance and magnetic resonance,Huygens'metasurfaces are imparted with high transmission and full phase coverage of 2π,which makes them capable of realizing high-efficiency wave-front control.However,a defect of Huygens'metasurfaces is that their phase profiles and transmissive responses are often sensitive to the interaction of neighboring Huygens'elements.Consequently,the original assigned phase distribution can be distorted.In this work,we present our design strategy of transmissive Huygens'metasurfaces performing anomalous refraction.We illustrate the investigation of Huygens'elements,realizing the overlapping between an electric dipole and magnetic dipole resonance based on cross-shaped structures.We find that the traditional discrete equidistant-phase design method is not enough to realize a transmissive Huygens'surface due to the interaction between neighboring Huygens'elements.Therefore,we introduce an extra optimization process on the element spacing to palliate the phase distortion resulting from the element interaction.Based on this method,we successfully design unequally spaced three-element transmissive metasurfaces exhibiting anomalous refraction effect.The anomalous refractive angle of the designed Huygens'metasurface is 30°,which exceeds the angles of most present transmissive Huygens'metasurfaces.A transmissive efficiency of 83.5%is numerically derived at the operating wavelength.The far-field electric distribution shows that about 93%of transmissive light is directed along the 30°refractive direction.The deflection angle can be tuned by adjusting the number of Huygens'elements in one metasurface unit cell.The design strategies used in this paper can be inspiring for other functional Huygens'metasurface schemes.
